Electrically heated forced air circulation oven



March 31, 1964 J. SAVIO ETAL ELECTRICALLY HEATED FORCED AIR CIRCULATION OVEN Filed Sept. 10, 1962 5 Sheets-Sheet 1 Z s R R m 0 E w WNW WM ,IPN A un a? March 31, 1964 J. SAVIO ETAL ELECTRICALLY HEATED FORCED AIR CIRCULATION OVEN 2 gm x? Q m .r um\ w .3 m 5 mm----:mm:w 1-, ww {Ill}lllwllilillb/ P N mm Q. 2 m w fin m m FF @Q INVENTORS J'osEPH Av/a Pun/v07. SCAIBEI? BY I W W ATTORNEYS March 31, 1964 Filed Sept. 10, 1962 J. SAVlO ETAL 3,127,499

ELECTRICALLY HEATED FORCED AIR CIRCULATION OVEN 5 Sheets-Sheet 3 mvzm-ons JOSEPH Snwo o1. AWD 7? See/p52 ATTORNEYS March 31, 1964 .1. SAVlO ETAL ELECTRICALLY HEATED FORCED AIR CIRCULATION OVEN Filed Sept. 10, 1962 5 Sheets-Sheet 4 ATTORNEYS 3,127,499 ELECTRICALLY HEATED FORCED AIR CIRCULATION OVEN Filed Sept. 10, 1962 March 31, 1964 J. SAVIO ETAL 5 Sheets-Sheet 5 'INVENTORS JOSEPH SAW/0 Roma/0 7". San/1E2 BY 4 m ATTORNEYS United States Patent 3,127,499 ELECTRICALLY HEATED FORCED AIR CIRCULATION OVEN Joseph Savio, Floral Park, and Roland T. 'S criber, Syosset, N.Y., assignors, by mesne assignments, to Market Forge Qompany, Everett, Mass, a corporation of Massachusetts Filed Sept. 10, 1962, Ser. No. 222,283 8 Claims. (Cl. 219-35) This invention relates to improvements in ovens, and, in particular, relates to an improved electrically heated oven provided with forced air circulation.

An important object of the invention is to provide an electric oven wherein the heating elements are concealed within the walls, and having means for maintaining a improved visual inspection of the interior and to provide improved door. opening means to improve access to the oven. i i

In accordance with a preferred embodiment of the invention, the oven comprises a casing having a peripheral wall and end walls, one of the end walls having doors for access. evenly distributed within the peripheral wall of the oven. The peripheral wa-ll transmits the resulting heat into the interior space of the oven. Further in accordance with the invention, a bafile plate is mounted in the casing in relatively closely spaced parallel relation to the end wall opposite the wall having the doors. The peripheral edge of the bafile plate is relatively closely spaced from the peripheral wall. The 'bafiie plate has a central opening. A high speed pump or fan is positioned and operative Electric heating means are provided relatively" v to draw air through the central opening of the bafile plate towards the adjacent end wall and then in a counterflow between the bafile plate and the end wall and back around the peripheral edge of the baffle plate.

The bafile plate has additional openings which are sized and positioned for flow through them towards the end wall of air drawn by the air flow between the battle plate and the adjacent end wall. In effect, the counterflow of the air draws air through the additional openings. The result is to provide a uniform flow of air through the center of the casing rearwardly and through the baflle plate, with a counterflow being set up around the periphery of the casing.

A working model of the oven has proven to be highly advantageous. As a result of the great uniformity of temperature and other advantages, it has been found possible to reduce baking time shrinkage greatly.

Another importance feature of the invention resides in the improved door construction for the front opening of the oven. The door construction comprises top door and bottom door mounted by lateral pivots to the sides of the oven, so that the top door is hinged at its top and the bottom door is hinged at its bottom. In accordance with the invention, sprocket wheels are provided in general vertical alignment respectively fixed on pivots of the top and bottom doors. An upper sprocket chain extends around the top of the upper sprocket wheel, and a bottom sprocket chain extends around the bottom of the lower sprocket wheel. Tensioned, flexible tape means in crossover relation connect the ends of the upper chain to the ends of the lower chain in such a way that downward 1 6, as shown in the closed position of FIG. 1.

31,127,499 Patented Mar. 31, 1964 outlet movement of the bottom door produces upward outward movement of the top door. With this construction, it is possible to provide different sprocket and chain ratios respectively for the top and bottom doors so that opening movement of the bottom door to horizontal position requires opening movement of the door to upwardly outwardly tilted position.

As the result of this mechanical arrangement, movement of the lower door degrees to convenient open position, corresponds to the door being upwardly outwardly tilted, to provide greater access space for entry into the oven.

Other objects and advantages of the invention will become apparent from the following description, in conjunction with the annexed drawing, in which a preferred embodiment of the invention is disclosed.

In the drawing:

FIG. 1 is a perspective view of the oven in accordance with the invention, the oven doors being shown closed.

FIG. 2 is a view similar to FIG. 1, the doors being shown open and certain of the working parts being shown diagrammatically in broken lines.

FIG. 3 is a vertical longitudinal section of the oven, the doors being shown open in full lines and closed in broken lines.

FIG. 4 is vertical cross-section on line 4-4 of FIG. 5. FIG. 5 is a horizontal cross-section on line 5-5 of FIG. 4.

FIG. 6 is a section on line 6-6 of FIG. 5 4

FIG. 7 is a fragmentary section on line 7 7 01 1 16. 5.

FIG. 8 is a fragmentary perspective view of a tray for insertion in the oven.

Upon particular reference to FIGS. 1 and 2 of the drawing, it will be noted that they show an oven 10 open at the front and having rear wall 12, and a peripheral wall structure consisting of top wall 13, side Walls 14 and and bottom wall 15. Top door 17 and bottom door 18 are norm-ally received within oven front opening FIG. 1 shows the doors 17 and 18 in coplanar, vertical closing position in which their adjacent edges meet and in which they seal the opening 16 into the interior space of oven 10. Said doors 17 and 18 are laterally pivoted respectively at their top and bottom to the side walls 14 and 140, so as to permit them to be pivoted to the opening position of FIG. 2. Handle 19 is affixed to the outside of door 17 for use in opening and closing the door.

Glass windows 20 and 21 are provided in door 17, and: glass Windows '22 and 23 are provided in door 1 8. Win: dows 21 and 23 are in vertical alignment in the door closed position of FIG. 1. Windows 20 and 2% are in vertical alignment also, with the windows 20 and 22' being located respectively on the opposite side of the vertical center line of doors 17 and 18 from the windows :21 and 22. Window 20 is located above the level of window 21, although with the lower edge of window 20 extending below the upper edge of window 211-. Window 2.2 is located above the level of window 23, although with the lower edge of window 22. extending below the upper edge of window 23. These windows are optionally rectangular, and the result is to permit viewing of the interior of oven 10 substantially at every vertical level, while at the same time providing a minimum of glass area with resultant dissipation of heat.

FIG. 2 shows a plurality of electric heating elements 24- locat ed within the interiors of the hollow peripheral walls, each of these elements 24 being generally U-shaped with longitudinal legs and affront connection portion 24a. Accordingly, the electric connections of the heating elements 24 may all be made at the rear. Each heating element 24 may comprise any normal resistance element appropriately sheathed, as is conventional, and the electrical connections for the heating elements 24 are conventional and are not shown in detail.

Optionally, there are three heating elements 24 in vertical spaced relationship in each side wall 14 and 140, two heating elements 24 in the bottom wall 15 (see FIG. 3) and one heating element in top wall 13. However, this arrangement may be appropriately varied as desired.

The specific wall construction is best shown in :FIGS. 3 and 4. As shown in these views, rear wall 12 has a rear panel 12a, a spaced front panel 12b, and an intermediate partition panel 1i2c, these panels being parallel to each other and vertically coextensive. As shown in FIG. 5, panel 12a extends laterally outwardly of the side edges of panels 12b and 12a. Panels 12b and 12c are laterally coextensive.

Wall 14 comprises outer panel 140, inner panel 14b and intermediate panel 14c. These panels are parallel to each other, with panel 14a connecting with the side edge of panel 12a, panel 14c connecting the side edges of panels 12b and 120, and panel 14b connected to panel 12b inwardly of the outer edge thereof, as shown in FIG. 5.

Similarly, wall 149 comprises outer panel 1 4%, inner panel 14% and intermediate panel 1400. These panels connect to the other sides of panels 12a, 12b and 120 similarly to the elements of wall 14, as shown in FIG. 5. The spacing between panels 14% and 1400 is greater than the spacing between plates 14a and 14c. Panels 140a and 14% extend forwardly of panel l ttle, and panels 14:: and 14b extend forwardly of panel 140, as shown in FIG. 5. The front opening between panel 14% and 14% is closed by panel 140d. The front opening between panels :14b and 14a is closed by panel 14d.

Top wall 13 consists of upper panel 131:, lower panel 13b and intermediate panel 130, all parallel to each other. Panel 1311 is connected to the upper edge of panels 12a, 12b and 120, as shown in FIG. 3, and is also connected to the upper edges of side panels 14a, 14b and 140 and 148a, 149k and 1406, as shown in FIG. 4. Panels 13b and 130 are respectively connected to panel 121) and also extend between and are connected to panels 14b and 14Gb. Panel 13c terminates rearwardly of the front ends of panels 13a and I131). Laterally and vertically extending partition panel 13d closed the front openings between panels 13a and 130 and between panels :13c and 18b, and extends between panels 14b and 14Gb. Panel 13b terminates rearwardly of the front edge of panel 14b. Panel 13a has a front edge 13g which has a wide notch (FIG. 1), the rear edge 13h of which is vertically aligned with the front edge of panel 13b. Vertically and laterally extending header panel l13e extending between edge 13h and the front edge of panel 11Gb and between panels 14b and 14Gb. Panel 13a is parallel to and spaced from panel 13d.

The structure of bottom wall 15 is similar to that of wall 13. Bottom wall 15 has a bottom panel 154:, top panel 15b and intermediate panel 150. Bottom panel \15a is of the same shape as panel 13a and is connected to the bottom edges of plates 12a, 12b and 120 and also extends between and is connected to the panels 14% and 14b. Panels 15b :and 15c are connected to panel 12b. Panel 15b extends between and is connected to panels 14b and 14%. Panel 15c extends between and is connected to panels 140 and 1400. Panels 14a, 14c, 140a and 140?: extend to panels 15a. Panels 14b and 140-b extend to panel 150.

Panels 15a and 15b extend forwardly of panel 150. Vertically and longitudinally extending panel 15d extends between panels 14b and 14% and closes the front open- 4 ings between panels 15b and 150 and between panels 15c and 15a. Panels 14b and 14% extend forwardly of panel 15b. Vertically and laterally extending panel extends between the front edge of panel 15b and the rear edge of the notch of panel 15a and also between panels 14b and 14%.

Panels 144m and tldtlb extend forwardly of panel 1 40c. Panels 14a and 14!) extend forwardly of panel 14c. Panel 1140c closes oi the front opening between panels 140a and 14% and extends between top panel 130 and bottom panel 15a. Similarly, panel 14 closes the front opening between panels 14m and 114b and extends between top panel 13a and bottom panel 15a. Said panels 14c and Mile together define the front of oven 10. The front opening 116 of oven is recessed and is defined by the bottom edge of panel 136, top edge of panel 15e and the inner side panels 14b and 14%. The panels 14b and 140b forwardly of panels 13a and 15s serve as bearings i for support of the lateral pivots of doors '17 and =18.

The result of the above construction is to form completelyenclosed inner compartments as follows: Inner top compartment 13] between panels 13b and 13c and panels 12b and 13d; inner rear compartment 12 between panels 12b and and panels 15a and 13a; inner bottom compartment 15 between panels 15b and 150 and panels 12b and 15d; inner side compartment 14] between panels 14b and 14a and panels 13a and 150; and inner side compartment 146 between panels 14% and 1490 and panels 13a and 15c.

The heating elements 24 are located in the respective compartments 14 14th, 131' and 15f. The ends of elements 24 are extended into wall 12 and there suitably interconnected, by means not shown, the connections being extended out of wall 12 (not shown) for connection to a voltage source. In addition, the inner compartments may be filled with insulation 25 of fiberglass or any other suitable material. This insulation is shown in FIG. 5, but is omitted in other views for convenience of illustration.

An outer compartment 26 is defined, extending between panels a and 14%, between panels 14a and 140, between panels 12a and 120 and between panels 13a and 15a. A further outer compartment 26a extends between panels 13a and 13c and panels 13d and 12b. Outer compartment 26b extends between panels 15a and 15a and panels 15d and 12b. Outer compartment 26c extends between panels 13d and 13a and panels 13a and 13b and panels 14b and 14%. Outer compartment 26d extends similarly to compartment 26c, except for being bounded by panels 15d and 15e.

The various outer compartments are left uninsulated and provide a dead air space, as a result of which the greater, part of the heat emitted by the elements 24 is transferred to the interior space of oven 10.

It will be understood that the panels can be formed and connected by any suitable means, in some instances by bending of sheet metal and in other instances by welding or other securing of sheet metal.

The Door Construction As best shown in FIGS. 2 and 3, each door 17 and 18 is of hollow core, rectangular metal construction. The interior space of each door is filled with insulation 30 of fiberglass or the like. Handle 19 is in the form of a laterally extending bar connected by studs 19a adjacent the respective ends thereof to the front panel of upper door 17. As shown in FIGS. 3 and 5, lateral pivots 31 extend out of the sides of the respective doors 17 and 18, adjacent the remote lateral edges thereof, said pivot pins being mounted in the doors by any suitable means (not shown). As shown in FIG. 5 for the upper doors, and in the detail view FIG. 7, the construction being similar for the lower door, the pivot pins 31 extend through suitable openings in panels 14b and 14% respectively, and extend through bearing blocks 32 respectively mounted upon the front faces of panels 14d and 140d. Said pins 31 further extend outwardly of panels 140 and 14% respectively. One of the pins 31 of lower door 18 extends into the space between panels 14a and 146, where one end of arm 34 is mounted on said pin 31. When door 18 is opened, the open end of arm 34 strikes stop 33 mounted between panels 14a and 140 (FIG. 4).

On the other side, the respective pins 31, which extend laterally outwardly of panel 1490, are coupled for movement in unison by means best shown in FIGS. 4 and 6. Sprocket wheel 41) is fixedly mounted upon upper pin 31, outwardly of partition panel 140, by means of hub 41. Sprocket wheel 42 is mounted upon the corresponding lower pin 31, by means of hub 43. Said sprocket wheels 40 and 42 are in general vertical alignment. Upper sprocket chain 43 extends around the top of upper sprocket wheel 4ft. Bottom sprocket chain 44 extends around the bottom of bottom sprocket wheel 42. Metal tape 45 is connected at one end thereof to one end of chain 43. Metal tape 46 is connected at one end thereof to the other end of upper sprocket chain 43. Turnbuckles 47 and 48 respectively connect the other ends of the tapes 45 and 46 to the respective ends of chains 44 in cross-over relation. As a result, if the upper door is moved by means of handle 19 from its closed position shown in FIG. 1 and shown in broken lines in FIG. 3, toward open position of FIGS. 2 and 3, sprocket 40 is moved in counterclockwise direction, the sprocket 42 is correspondingly moved in clockwise direction, so that the lower door 18 is also opened. Conversely, closing of door 17 causes closing of door 18. Ann 54- extends generally rearwardly when the doors are closed. Opening of door 18 moves arm 34 until it extends generally upwardly and strikes stop 33, stopping further opening movement. At this point, optionally, door 18 is horizontal.

An important feature of this construction is that it is possible to have different sprocket and chain ratios, so that selected movement of the lower door requires a different movement of the upper door. Specifically, the teeth of the sprockets may hear such ratios, with corresponding ratios of the chain openings, so that movement of the upper door more than 90 degrees is required to produce the optional ninety degree opening movement of the bottom door, as shown in FIG. 3. Thus, the ratios may be selected so that the upper door moves about 105 degrees in order to bring the lower door to its final 90 degree movement. This can be accomplished because there is not a continuous chain, the chains instead being connected by the tapes and turn buckles. The tapes can be secured to the chain ends and turn buckles by any suitable pivot means which need not be described in detail. The turn buckles 47 and 48 me conventional and need not be described in detail. Generally speaking, any suitable turn buckle may be employed, but by way of example the turn buckle 48 may have a central collar 49 into which screws 50 extend, these screws 56 being respectively connected to the chain end and tape end. As a result, by appropriate turning of collar 49, the tension may be adjusted.

Forced Draft Fan and Bafil'e Construction The interior of the oven is clearly shown in FIGS. 2, 3, 4, 9 and 10.

Generally planar bafile plate 519 is mounted in the interior of oven 11) is relatively closely spaced parallel relation to the rear vertical end wall panel 12b. Said ballle plate 59 is generally square. As best shown in FIGS. 9 and 10, threaded studs 51 are fixed to plate 50 adjacent the corners thereof and extend rearwardly thereof, through openings in panel 12b. Nuts 52. and 53 are threaded onto stud 51 respectively inwardy and outwardly of panel 21]) and are tightened so as to secure stud 51 axially adjustably to panel 12b. Panel 56 has a central circular opening 54. Longitudinally extending drive shaft 55 is aligned axially with the center of hole 54 and extends through a sleeve bearing 56 which extends through and is mounted in an opening of panel 121). As shown in FIG. 3, this sleeve bearing 56 also extends through and is mounted in openings of panels 12c and 12a. Shaft 55 extends through sleeve bearing 56 and rearwardly of wall 12, where drive pulley 57 is mounted upon shaft 55. Belt 58 on pulley 57 is connected to any suitable source of power (not shown) so as to rotate shaft 55. Hub 59 is mounted upon shaft 55 forwardly of panel 12b by means of set screw 60. Squirrel cage fan or convector 61, of diameter slightly greater than that of hole 54, is fixed to hub 59. Any appropriate fan may be utilized, this particular fan having a rear wall 62 mounted upon hub 59, being open at the front and having a peripheral wall 63 with slots and fins 64 so as to suck in air through the front opening and through opening 54 and to exhaust said air between the fins 64 outwardly of the periphery of the fan.

The peripheral edge portions of bafile plate 5i? are bent rearwardly so as to define peripheral edge flanges 65. Each said flange 65 is rearwardly inclined at an angle of approximately 45 degrees to the plane of plate 50. The free edges of flanges 65 may be considered as the peripheral edge of the battle plate and are relatively closely spaced from the respective panels 14b, 149b, 13b and 15b, which may together he considered as the peripheral wall of the inner space of oven lll. In View of the fact that this inner space is slightly wider than high, the side flanges 65 are spaced slightly further from the sides of the oven than the top and bottom flanges 65 are spaced from the top and bottom walls.

The effect of the above described arrangement is to cause the air movement means (the fan) to draw air through the central opening 54 towards the end Wall panel 12b and then in a counterfiow between baflle plate 54 and end wall panel 12b and back around the peripheral edge of bathe plate 50. As an important feature of the invention, baffle plate 50 has additional openings 66 sized and positioned for flow through said additional opening 66 towards said end wall panel 12b of air drawn by the air flow between bafile plate Sll and end wall panel 12b. Put in other terms, these openings 66, located radially outwardly of opennig 54, result in a suction being produced through said openings by the above mentioned counterfiow of the air, thereby drawing air rearwardly through the opening 66. This diffuses the air movement rearwardly through the baffie plate and prevents it from being concentrated centrally. The eifect is to produce a more uniform air movement both the main movement rearwardly through the main portion of the oven and the counterflow around the periphery thereof.

Preferably, the openings 66 are arranged in concentric rings A and B. The openings of each ring are substantially equally spaced circumferentially. The openings of ring A are located circumferentially between respective openings of ring B. In the embodiment illustrated, ring A has four openings respectively located at 12 oclock, 3 oclock, 6 oclock and 9 oclock. Ring B has eight openings, respectively located substantially at 12:45, 2:15, 3:45, 5:15, 6:45, 8:15, 9:45 and 11:15 measured along the radial line extending from the center of opening 54 through any of the openings 66. Opening 66 is less than halfway between the center of opening 54 and the periphery of plate 50, and the opening 66 of ring B is on a circle more than halfway between the center of opening 54 and the periphery of plate 50.

Reference is made to FIG. 9, which is substantially to scale, to show the particular arrangement of the holes.

In order to disrupt the air flow, and further improve the uniformity of air flow, a disruptor device is located over opening 54. This disruptor device includes horizontal bars 71) and 71 which extend across opening 54, on the front face of plate 50, and are secured to plate 51 by any suitable means. Specifically, these bars 70 and 71 may be parallel to each other and may have front lateral ribs 70a. The width of each rib 7021'is less than the width of each bar 71. At their ends, the rear faces of bars 70 are connected to vertical strap plates 72. These strap plates 72 are vertically adjustably secured to platelStl by means of clips 73 made of bendable metal. Each said clip 73 is U-shaped with its bight extending through a respective 3 oclock or 9 oclock hole 66 of ring A with the rear legs of each clip 73 respectively abutting the rear face of plate '0 and the front leg 73a of clip 73 is welded to the front of strap 72. Preferably, the leg 70 is located closer to the top of hole 54 than the leg 71 is located to the bottom of hole 54, or in other words, the element is displaced vertically off center.

On each side of opening 54, plate 50 has upper and lower apertured lugs 201 struck forwardly therefrom, as shown in FIG. 9. A vertical rod 260 (FIG. omitted in FIG. 9) passes through the apertures of each pair of lugs 200 to space the baking racks or trays from plate 50 and thereby ensure proper air circulation.

The Racks As shown in FIG. 8, rack 80 is defined by a peripheral, generally rectangular tubing frame 81. A series of longitudinally extending rods 82 are laid over the front and rear sides of the tubing frame 81 and secured thereto by any suitable means. The side legs 81a of frame 81 are received in channels 83 fixed to the respective side panels 14b and 14012. There are two such channels 83 in coplanar relationship at each level upon which it might be desired to place a rack. Each said channel 83 has a side portion fixed to the wall and upper and lower arms 83a. The side tubing leg 81a is slidably received between the arms 83a, with the width of the frame being suificient to ensure that the respective sides 81a will be received in the respective channels. One or more spring clips 84 are fixed to the top of each tubing side 81a. As shown in FIG. 8, said clip 84 is made of a strap of flexible and resilient metal having its ends fixed by any suitable means to the frame and having its center portion 84a upwardly bowed. When the rack is inserted in place, the spring clip 84a frictionally engages the upper arm 83a, thereby ensuring that the rack is held frictionally in place without possibility of rattling under the high velocity of air flow within the oven.

Conclusion The action of the fan and of the doors having been described under the respective headings, the overall operation of the oven need not be further summarized. It will be sufiicient to point out that the uniform air fiow through the interior of the oven results in a uniformity of temperature throughout the oven. It has been found possible to cook meat satisfactorily at a low temperature of 200225 F., with a pan of water maintained in the oven, with a roast shrinkage as low as 56%. At the same time, the oven is highly more efficient and economical to operate than a convection gas oven.

While a preferred embodiment of the invention has been disclosed, and various possible changes, omissions and additions have been indicated, it will be apparent that various other changes, additions and omissions may be made in the invention without departing from the scope and spirit thereof.

Wh'at is claimed is:

1. An oven comprising a casing having a peripheral wall, end walls, heating means in said peripheral wall, said peripheral wall transmitting said heat into the interior space of said peripheral wall, a batfle plate, means mounting said baffle plate in said casing in relatively closely spaced parallel relation to one end wall, the peripheral edge of said bafiie plate being relatively closely spaced from said peripheral wall, said bafile plate having a central opening, and air movement means positioned and operative to draw air through said central opening towards said one end wall and then in a counterfiow be- :tween said bafiie plate and said one end wall and back :around said peripheral edge of said bafile plate, said lzafile plate having additional openings sized and positioned for flow through said additional openings towards 'said one end wall of air drawn by the air flow between said baffle plate and said one end wall.

2. Oven according to claim 1, said additional openings being all smaller than said central opening and being arranged in inner and outer rings of circumferentially spaced additional openings concentric with said central opening.

3. Oven according to claim 2, said additional openings being equally spaced in each ring.

4. Oven according to claim 2, said oven also comprising spaced parallel bars mounted on said baffle plate extending across said central opening, the center of said central opening being between said bars and closer to the lower bar than to the upper bar, said bars being parallel to the bottom of the oven.

5. Oven according to claim 1, said casing having an inner chamber adjacent the interior space of the casing and surrounding said interior space and an outer chamber surrounding said inner chamber, said heating means being in said inner chamber, and insulation located in said inner chamber, said outer chamber being closed so as to contain dead air therein.

6. Oven according to claim 1, the entire peripheral edge portion of said baffle plate being inclined towards :said one end wall.

7. Oven according to claim 3, the entire peripheral edge portion of said baffle plate being inclined towards said one end wall.

8. Oven according to claim 1, comprising at least one bar mounted on the baffle plate across the center opening operative to retard the flow of air through said opening.

References Cited in the file of this patent UNITED STATES PATENTS. 

1. AN OVEN COMPRISING A CASING HAVING A PERIPHERAL WALL, END WALLS, HEATING MEANS IN SAID PERIPHERAL WALL, SAID PERIPHERAL WALL TRANSMITTING SAID HEAT INTO THE INTERIOR SPACE OF SAID PERIPHERAL WALL, A BAFFLE PLATE, MEANS MOUNTING SAID BAFFLE PLATE IN SAID CASING IN RELATIVELY CLOSELY SPACED PARALLEL RELATION TO ONE END WALL, THE PERIPHERAL EDGE OF SAID BAFFLE PLATE BEING RELATIVELY CLOSELY SPACED FROM SAID PERIPHERAL WALL, SAID BAFFLE PLATE HAVING A CENTRAL OPENING, AND AIR MOVEMENT MEANS POSITIONED AND OPERATIVE TO DRAW AIR THROUGH SAID CENTRAL OPENING TOWARDS SAID ONE END WALL AND THEN IN A COUNTERFLOW BETWEEN SAID BAFFLE PLATE AND SAID ONE END WALL AND BACK AROUND SAID PERIPHERAL EDGE OF SAID BAFFLE PLATE, SAID BAFFLE PLATE HAVING ADDITIONAL OPENINGS SIZED AND POSITIONED FOR FLOW THROUGH SAID ADDITIONAL OPENINGS TOWARDS SAID ONE END WALL OF AIR DRAWN BY THE AIR FLOW BETWEEN SAID BAFFLE PLATE AND SAID ONE END WALL. 